The invention relates to a spin chuck used in a chamber, in particular, to a spin chuck capable of providing simultaneous dual-sided processing (including cleaning processes), and capable of widely adjusting the angular velocity and angular acceleration thereof.
In a conventional manufacturing process of a semiconductor device or a liquid crystal display (LCD) including wet etching, cleaning, wet spin etching, coating, and developing, various types of acid tanks or chambers are utilized. In a conventional chamber, a wafer or LCD substrate is clamped on a chuck that is driven to rotate by a driving device (e.g. a motor).
A conventional driving system utilizes a single motor as a driving source. A wafer clamped on a chuck is driven to rotate as shown in U.S. Pat. No. 5,312,487.
Referring to FIG. 1, a conventional driving system of a spin chuck for driving a substrate 101 to rotate includes a motor 102, a chuck 104, and a controller 105. The motor 102 includes a rotating shaft 103. The rotating shaft 103 drives the chuck 104, used to clamp a substrate 101, to rotate. The controller 105 is used for controlling the angular velocity of the motor 102. The substrate 101 is clamped on the chuck 104 by way of vacuum pressure. Therefore, the driving system further includes a vacuuming conduit 106 penetrating through the motor 102.
In the driving system, the chuck 104 is driven by the motor 102 to rotate substrate 101. The end product of the complicated processes substrate 101 undergoes is determined by the properties of the processing materials, the patterns on the substrate 101, the angular velocity control and the angular acceleration control of the substrate 101, among others. After the processing materials and the patterns on the substrate 101 are determined, control over both angular velocity and angular acceleration of the substrate 101 becomes an important issue.
Referring to FIG. 2, the horizontal axis represents time, and the vertical axis represents the rotation speed of the substrate. Time t is the time required for the substrate to increase its rotation speed from 0 to N (where N is an integer) rpm (revolutions per minute). A line 107 represents the speed variation of the substrate. Time t is also the time required for the substrate to decrease its speed from 0 to xe2x88x92N rpm. A line 108 represents the speed variation of the substrate. The maximum rotation speed of the substrate is N or xe2x88x92N rpm.
A line 109 represents the rotation speed of the substrate after it reaches N rpm, while a line 110 represents the rotation speed of the substrate after it reaches xe2x88x92N rpm. An area 111 shaded with diagonal lines is the speed variation of the substrate. The maximum angular acceleration of the substrate can be determined from the slopes of lines 107 and 108.
In general, variations in the angular velocity and the angular acceleration of the motor 102, which drives the substrate 101, are ideally as large as possible. However, after the motor 102 is manufactured, the performance (e.g., the maximum instant torque, the maximum rotating speed, the minimum rated rotating speed, the maximum angular acceleration, and related characteristics) of the motor 102 and those of the controller 105 are fixed. When the motor 102 is designed for rotating at high speeds, its rotation condition is not stable or easily controlled at low rotation speeds. In addition, when the motor 102 is designed for rotating at low rotation speeds, its rotation condition is not stable or easily controlled at high rotation speeds.
Recently, the line widths of semiconductor products have greatly decreased. More time is needed for the processing material to fill into the narrow trenches and cover the surfaces of the trenches. After the processing material has filled into the narrow trenches, the redundant processing material cannot be ejected from the trenches due to the surface tension of the processing material. In order to avoid this phenomenon, the driving system has to provide greater angular velocity or angular acceleration to force out the redundant processing material in the trenches.
The design of the motor 102 or controller 105 can be improved to let the angular velocity and the angular acceleration of the motor 102 satisfy the process requirements. However, it is extremely difficult for a single set of one motor 102 and one controller 105 to reach wide controls of angular velocity and angular acceleration, unless the manufacturing costs of the motor 102 and the controller 105 are increased. Even then, a motor 102 and a controller 105 are often unable to satisfy the process requirements.
In a conventional spin chuck driving system, a motor is in direct contact with a chuck. Thus, the heat energy generated from the motor is easily transferred to the chuck, causing the substrate temperature to rise. Furthermore, since the tangential velocity of the circumferential edge of the rotating substrate relative to the air is high, the heat energy at the circumferential edge of the substrate is easily transferred to the air. In addition, since the tangential velocity at the center of the rotating substrate relative to the air is low, the heat energy at the center of the substrate is not easily transferred to the air. As a result, a temperature difference between the circumferential edge and the center of the substrate is induced, which deteriorates the qualities of product.
FIG. 3A is a front cross-sectional view illustrating a flow status of an etchant on a substrate in a conventional etching process. FIG. 3B is a top view illustrating a flow status of an etchant on a substrate in a conventional etching process. FIG. 3C is a front cross-sectional view illustrating the etched substrate as shown in FIG. 3A. FIG. 3D is a top view illustrating the etched substrate as shown in FIG. 3B.
Referring to FIGS. 3A and 3B, an etchant 121 flows through a trench 123 of a substrate 122. An arrow indicates the direction of flow of the etchant 121. In the prior art, the direction of flow of the etchant 121 is fixed because the rotation direction of the substrate 122 is fixed. FIGS. 3C and 3D show the change in the trench patterns and the deteriorating quality of the substrate from the etching process.
In order to prevent the lower surfaces of the wafers or LCD substrates from having direct contact with a spin chuck, a spin chuck using a protective layer of gas and a clamp pin, as disclosed in U.S. Pat. No. 5,421,056, is used. A schematic illustration of the above spin chuck is shown in FIG. 4A.
Referring to FIG. 4A, the spin chuck 141 has six clamp pins 142. The clamp pins 142, that clamp or release substrate 140, form a ring that is adjusted by an extension rod (not shown) and a swingable lever. A supply passage 143 is provided within the spin chuck 141 to support the substrate 140 using a flow of gas. It should be noted that the arrow indicates the gas""s direction of flow.
The substrate 140 is not in direct contact with the spin chuck 141, solving substrate 140""s lower surface pollution problem. However, because there is no relative motion between each of the clamp pins 142 and the substrate 140, unwanted pin marks 144 are easily formed in the contact regions between each of the clamp pins 140 and the substrate 140, as shown in FIG. 4B. Therefore, uniform product quality is not easily obtained.
It is therefore an object of the invention to provide a spin chuck capable of providing simultaneous dual-sided processing (including cleaning processes), wide ranges of angular velocity and angular acceleration, and uniform substrate quality. The spin chuck in accordance with the invention can rotatably clamp the outer periphery of the substrate so as to provide simultaneous dual-sided processing.
In accordance with an aspect of the invention, a spin chuck used for clamping a substrate to rotate in a chamber includes three roller shafts and three clamping rollers. The respective roller shafts are driven to rotate by a planetary gear transmission mechanism. The planetary gear transmission mechanism includes a gear shaft driven to rotate by a driving device, and three output shafts. The rotation speed of each of the three output shafts has a predetermined relationship with the rotation speed of the gear shaft so as to drive each of the three respective roller shafts to rotate. The three clamping rollers are fixed on the three roller shafts, and are driven to rotate by each of the three respective roller shafts so as to rotatably clamp the substrate.
In accordance with another aspect of the invention, a spin chuck used for clamping a substrate to rotate in a chamber includes a body, an input/output conduit, a gear shaft, two conoids, a frame, a planetary gear transmission mechanism, three roller shafts, and three clamping rollers.
The body is driven to rotate by a driving device, the body has a through hole penetrating through the body, a first space substantially perpendicular and communicating with the through hole, three holes allowing the first space to communicate with the outside, a plurality of upper guiding portions communicating with the first space and located above the first space, and a plurality of lower guiding portions communicating with the first space and located below the first space.
The input/output conduit penetrates through the through hole and is for supplying a predetermined processing material to the substrate and for allowing a predetermined processing material drain out.
The gear shaft is received in the through hole and rotatably mounted between the body and the input/output conduit. The two conoids are rotatably mounted on the gear shaft and each conoid is separated from the other by a predetermined distance. Each of the conoids has a plurality of slanting guiding portions.
The frame is received in the body and includes a plurality of section-shaped sub-frames. Each of the sub-frames has a gear-room, and an upper sliding portion and a lower sliding portion. The upper and lower sliding portions are located above and under each sub-frame""s respective gear-room. The upper sliding portion shifts within the upper guiding portion, while the lower sliding portion shifts within the lower guiding portion.
Each of the sub-frames further includes an upper shifting portion and a lower shifting portion located at the inner periphery of the sub-frame and spanning from the top to the bottom which allows shifting within the slanting guiding portion while the frame is being enlarged and reduced by the two conoids and the plurality of slanting guiding portions.
The planetary gear transmission mechanism is received in the gear-room, it includes a sun gear, three planet gears, and three output shafts. The sun gear is fixed on the gear shaft between the two conoids with the gear shaft serving as a rotating shaft. The three planet gears are arranged around the sun gear. The three output shafts are fixed on the three planet gears and penetrate through the frame.
The three roller shafts are received within the gear shafts and driven to rotate by the three output shafts. The three clamping rollers are mounted to the three roller shafts to rotate and rotatably clamp the substrate.